pub fn lession_1() {
    //byte string
    let bytestring: &[u8;21] = b"this is a byte string";
    println!("A byte string: {:?}",bytestring);

    //打印字节串
    let escaped = b"\x52\x75\x73\x74 as bytes";
    println!("Some escaped bytes: {:?}",escaped);

    //字节串与原始字面量结合
    let raw_bytestring = br"\u{211D} is not escaped here";
    println!("{:?}",raw_bytestring);
}
